1) Print out the elements of the following array: int [] numbers = {1,2,3,4,5};
int [] numbers = {1,2,3,4,5}; for (int i = 0; i < numbers.length; i++) { System.out.println(numbers[i]); } // OR for(int element : numbers) { System.out.println(element); }
2) Declare and initialize a String array containing the days of the week. Print out a random day.
String [] days = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" }; int random = (int)(Math.random()*days.length); System.out.println(days[random]);
3) Output the sum of the elements in this array int [] values = {3,5,4,7,2,3};
int [] values = {3,5,4,7,2,3}; int sum =0; for(int i = 0; i < values.length; i++) { sum+=values[i]; } System.out.println(sum); //OR if you have Java 8... sum = IntStream.of(values).sum(); System.out.println(sum);
4) Output the average of the elements in this array int [] values = {3,4,5,6};
int [] values = {3,4,5,6}; int sum =0; for(int i = 0; i < values.length; i++) { sum+=values[i]; } System.out.println((double)sum/(values.length)); //OR if you have Java 8... double average = IntStream.of(values).average().getAsDouble(); System.out.println(average);
5) Declare an int array of length 5. Use a for loop to prompt for 5 numbers and enter them into the array. Print out the array.
int [] numbers = new int[5]; Scanner scan = new Scanner(System.in); for (int i = 0; i<numbers.length;i++) { System.out.println("Enter a number"); int n = scan.nextInt(); numbers [i] = n; } System.out.println("... and your numbers are... "); for (int i =0; i<numbers.length; i++) { System.out.println(numbers[i]); }
6) Declare an int array of length 4. Use a for loop to prompt for 4 numbers and enter them into the array. Print out the average of the four numbers
int [] numbers = new int[4]; Scanner scan = new Scanner(System.in); for (int i = 0; i<numbers.length;i++) { System.out.println("Enter a number"); int n = scan.nextInt(); numbers [i] = n; } int sum =0; for (int i =0; i<numbers.length; i++) { sum += numbers[i]; } System.out.println("Average: " + (double)sum/numbers.length);
7) The following code will convert a String s to an array of characters c. Print out the characters: String s = “This is a string”; char [] c = s.toCharArray();
String s = "This is a string"; char [] c = s.toCharArray(); for(char e: c) { System.out.print(e+","); } System.out.println("");
8) Use what you learned in the last question to count the number of times the letter e occurs in the String “I never saw a purple cow”
String s = "I never saw a purple cow"; char [] c = s.toCharArray(); int count = 0; for(char e: c) { if (e == 'e') count++; } System.out.println("Number of e's: "+ count);